1. Field of the Invention
The present invention relates to a bearing mechanism used in a motor.
2. Description of the Related Art
Some known motors used in disk drive apparatuses include a bearing mechanism using fluid dynamic pressure. In a spindle motor disclosed in FIG. 1 of JP-A 2009-136143, a bottom plate 10, a first bearing component 16, a second bearing component 18, and a fixed shaft 12 are stationary components. Radial fluid dynamic pressure bearing portions 22a and 22b are defined between the fixed shaft 12 and a rotor component 14. A thrust fluid dynamic pressure bearing portion (i.e., a thrust bearing portion) 26 is defined between the first bearing component 16 and the rotor component 14. A pumping seal 36 is defined between the second bearing component 18 and the rotor component 14. The rotor component 14 includes a circulation channel 28 defined therein. The circulation channel 28 is arranged to join a radially outer region of the thrust bearing portion 26 and a radially inner region of the pumping seal 36 to each other. A seal gap 34 is arranged radially outside the thrust bearing portion 26.
In the case where, as in the spindle motor disclosed in JP-A 2009-136143, a mouth of a communicating channel, i.e., a circulation channel, and a thrust dynamic pressure bearing portion overlap with each other, a sufficient dynamic pressure may not be easily obtained. Also, if the thrust dynamic pressure bearing portion is provided so as to avoid the mouth of the communicating channel, the thrust dynamic pressure bearing portion has to be small, and a sufficient dynamic pressure may also not be obtained. As a result, a rotating portion may not be sufficiently lifted, and abrasion may easily occur on opposing surfaces of the rotating portion and a stationary portion.
Accordingly, there is a demand for a bearing mechanism in which the thrust dynamic pressure bearing portion is increased in size.